Ad-hoc network has been known as an autonomous distributed network. In the ad-hoc network, a large-scale network is formed autonomously, and the communication is maintained when a trouble occurs. In addition, the ad-hoc network is applicable to various communication media, either wired or wireless communication.
The ad-hoc network has been applied to a sensor network for example. In a wired sensor network, each node equipment is connected to a plurality of node equipments by wired connection, and data communication and power supply are performed by wired connection. Some of the advantages of the wired type are that it is possible to embed the sensor into the ground, water, structural objects and the like, and that it is possible to detect disconnection and the like.
In order to establish an ad-hoc network, a technique to select the optimal path, a control technique in case of trouble, and the like may be required.
As routing control in the ad-hoc network, the following technique is known. The sensor included in a communication node of the ad-hoc network has a function as a sensor node and a function as a relay node. Each node executes the routing process based on the adjacent node information, destination address, source address and the frame sequence number. Upon receiving a frame, the node compares the received frame with the contents of a destination table that the node has, and transmits the frame by selecting a transmission port that is different from the reception port. When there are a plurality of available communication ports for transmission, selection is made according to a condition such as the ascending order or the descending order of the port number. Related techniques are described in, for example, Japanese Laid-open Patent Publication No. 2002-368789.
However, when the routing in the ad-hoc network is performed in the known scheme, the path may not necessarily be determined with a smallest hop count, and the determined path may be redundant.